The present invention relates to a sealing arrangement for a sliding bearing for carrying heavy loads, in which two plate-shaped bearing sections of metal, displaceable relative to each other, are provided with sliding plates fastened between them. One of the plates is larger than the second one. Lubrication is applied between the sliding plates. A sealing strip encloses the sliding surface at a distance and carries the smaller sliding plate as well as adheres to the larger sliding plate. Between the sealing strip and the sliding surface or smaller sliding plate a gap is formed.
When using bearings for heavy loads it is necessary to keep the friction losses as small as possible. To achieve this, much attention must be given to the selection of suitable sliding mating parts or sliding materials; also, care must be taken that the lubrication of friction surfaces is most efficient and long-lasting. However, because of the heavy loads, the build-up of a lubricating film is greatly impeded and, if such a lubricating film is actually present (e.g., directly after installing a bearing if the sliding surfaces are lubricated before installation), squeezing out of the lubricant layer from the sliding surfaces occurs due to the relative motion of the sliding mating parts against each other.
Another problem is that the entry of dirt from outside the bearing into the sliding surface is effectively prevented. Upon the entry of dirt or other contamination into the sliding surface, not only is the lubricant film that is present there disturbed, but there is increased abrasion and an unwanted rise of the friction coefficient of the sliding bearing.
With a known bridge bearing (German Pat. No. 1,230,826), an attempt has been made to ensure the feeding of lubricant into the lubricant of the sliding layer by providing lubricant storage locations in one of the two sliding surfaces which are made of polytetrafluoroethylene. However, with this bearing, the lateral squeeze-out of lubricant cannot be prevented. For this reason servicing the bearing throughout its useful life is indispensible. Also, no measures are provided to prevent the entry of foreign matter from the outside.
Further attempts have been made to relieve the sliding bearing from the acceptance of so-called "minimum movements" by combining such a sliding bearing, provided with lubricant storage cells in one sliding surface, with a deformation bearing. These "minimum movements" arise from traffic movements, etc. As a result, after the decay of movements, occurring within a certain period after installation of the bearing, resulting from pre-tension, creep and fading, during the subsequent period the deformation bearing, which by itself requires no maintenance, must be effective to receive the still remaining movements. However, up to that time, the full effectiveness of the sliding bearing mnust be maintained: since with these known bearings neither measures against the squeezing out of lubricant from the sliding surface nor against the entry of dirt from the outside have been described before, continuous servicing of the bearing remains indispensable at least during the period when larger movements require the full effectiveness of the sliding bearing.
In order to combat the contamination of the sliding surfaces, various technical approaches were made. The "Texte der allgemeinen bauaufsichtlichen Zulassungen (texts of general building permit regulations)" (as of May 1973--cited from: Eggert/Grote/Kauschke: "Lager im Bauwesen (bearings in the construction industry)" provide that "the sliding surfaces ought to be protected suitably against contamination (dirt)." In section 6.2.7 (corrosion and dirt) the use of bellows located horizontally underneath the sliding surfaces is recommended. With other known sealing arrangements for such sliding bearings for carrying heavy loads, a sealing strip enclosing the sliding surface at a distance, is fastened to the smaller sliding plate and adheres to the larger sliding plate.
These known sealing arrangements are well suited for effectively preventing contamination, etc., of the sliding bearing from the outside. However, the squeeze-out of lubricant from the sliding surface under high pressure is not yet prevented or eliminated by the known sealing arrangements; for this reason sliding bearings for heavy loads equipped with such sealing arrangements require a continuous servicing of the sliding bearing; this in turn makes it necessary that the sealing arrangements used can be easily disassembled.
Based on this state of the art, it is the object of the present invention to provide a sealing arrangement of the above type in such a way that preservation of the lubricant layer between the sliding surfaces of the sliding bearing lasts longer than with previously known sealing arrangements, and at the same time effectively preventing the entry of dirt, etc., from outside the bearing.
Another object of the present invention is to provide an arrangement of the foregoing character which is substantially simple in construction and may be economically fabricated.
A further object of the present invention is to provide an arrangement, as described, which may be readily maintained in service and which has a substantially long operating life.